The present invention relates to specific compositions made by alkoxylation of crude guerbet alcohol mixtures that contain between 15% and 50% lower molecular weight alkoxylated alcohols. The lower molecular weight alcohols are the raw material alcohols used to make the guerbet. Compositions containing this specific bi-modal distribution have unique emulsification properties.
Guerbet alcohols have been known for over 100 years now. Marcel Guerbet pioneered the basic chemistry in the 1890s. It has allowed for the synthesis of a regiospecific beta branched hydrophobe which introduces high purity, branching into the molecule. Guerbet Alcohols, the oldest and best-understood material in the class of compounds, have been known since the 1890""s when Marcel Guerbet 1 first synthesized these materials. The reaction sequence, which bears his name, is related to the Aldol Reaction and occurs at high temperatures under catalytic conditions. 
The product is an alcohol with twice the molecular weight of the reactant alcohol minus a mole of water. The reaction proceeds by a number of sequential steps. These steps are (a) oxidation of alcohol to aldehyde, (b) Aldol condensation after proton extraction, (c) dehydration of the Aldol product, and (d) hydrogenation of the allylic aldehyde. The reaction takes place without catalyst, but it is strongly catalyzed by addition of hydrogen transfer catalysts. At low temperatures 130-140xc2x0 C. the rate-limiting step is the oxidation process (i.e. formation of the aldehyde). At somewhat higher temperatures 160-180xc2x0 C. the rate-limiting step is the Aldol Condensation. At even higher temperatures other degradative reactions occur and can become dominant.
Many catalysts have been described in the literature as effective for the preparation of Guerbet Alcohols. These include, nickel, lead salts (U.S. Pat. No. 3,119,880), Oxides of copper, lead, zinc, chromium, molybdenum, tungsten, and manganese (U.S. Pat. No. 3,558,716). Later US patents (U.S. Pat. No. 3,979,466) include palladium compounds and silver compounds (U.S. Pat. No. 3,864,407). There are advantages and disadvantages for each type.
The Cannizzaro Reaction is a major side reaction and is described as the disproportionation of two molecules of an aldehyde brought about by the action of sodium or potassium hydroxide to yield the corresponding alcohol and acid. On a practical level, it results in a product that is both difficult to purify and has undesired products present. The ability to capitalize upon the Guerbet reaction and develop useful cost effective derivatives has resulted eluded scientists for many years.
A major problem with the currently used Guerbet products is the fact that they are sold as very high purity products, requiring elaborate clean up processes and post treatments to make products that find applications mostly in cosmetic products. Guerbet alcohols undergo a series of post reaction steps that (a) remove unreacted alcohol (vacuum stripping), (b) remove unsaturation (hydrogenation), (c) remove Cannizzaro soap (filtration) and (d) remove color/odor bodies. These operations add to the cost of the product and make the utility impractical. All inventions covering Guerbet alcohols and their derivatives were made using highly purified materials, which not only limited the usefulness due to costs, but also as will become apparent by this disclosure, resulted in mono-modal surfactants that lack the highly efficient emulsification properties that result when using lower purity products. By lower purity products is meant those products in which unreacted raw material alcohol is left in the mixture and subsequently co-alkoxylated to give bi-modal surfactants, having unique emulsification properties.
Most commonly alcohols of natural origin, which are straight chain, even-carbon, primary alcohols are used for the production of Guerbet alcohols. Guerbet alcohols are beta branched primary alcohols. Oxo alcohols can also be used, but the reaction rate and conversions are reduced.
We have surprisingly found that upon alkoxylation of a low purity guerbet alcohol, a bi-modal alkoxylate occurs having outstanding emulsification properties. These emulsifiers are outstanding when used with crude petroleum and other non-polar compounds.
It is an objective of the present invention to provide unique bi-modal alkoxylated emulsifiers. These bi-modal emulsifiers are made up of between 50 and 90% by weight of a guerbet alcohol alkoxylate and between 10% and 50% by weight non-guerbet starting alcohol alkoxylate.
It is another objective of the present invention to provide a process for making emulsions using the unique bi-modal alkoxylated emulsifiers of the present invention.
The current invention is aimed at a bi-modal alkoxylated emulsifier made by the alkoxylation of a partially reacted crude guerbet alcohol. We have surprisingly found that when the guerbet reaction is carried out to between 50% and 75% many important, heretofore unrecognized benefits occur. The first is that the Cannizzaro reaction is almost nil, second the formation of higher molecular weight species likewise is almost nil, thirdly the reaction time is significantly reduced, yields are increased and most importantly when the resulting composition is alkoxylated with ethylene oxide, propylene oxide and mixtures thereof, unique very efficient bi-modal emulsifiers result.
The current invention relates to a bi-modal emulsifier composition, which comprises:
(a) between 10% and 50% by weight of an emulsifier which conforms to the following structure:
CH3(CH2)nxe2x88x92Oxe2x80x94(CH2CH2O)a(CH2CH(CH3)O)bxe2x80x94(CH2CH2O)cxe2x80x94H
xe2x80x83wherein;
n is an integer ranging from 5 to 19;
a, b, and c are independently each integers ranging from 0 to 20, with the proviso that a+b+c be greater than 5;
and
(b) between 90% and 50% of an emulsifier which conforms to the following structure: 
xe2x80x83wherein;
y is an integer ranging from 5 to 19, and is equal to n;
x is an integer ranging from 3 to 17 with the proviso that x=y+2
a, b, and c are independently each integers ranging from 0 to 20, with the proviso that a+b+c be greater than 5.
Another aspect of the invention is drawn to a process for making an emulsion, which comprises mixing;
(1) between 1% and 50% by weight of a water insoluble oil,
(2) between 98% and 35% water
and
(3) between 1% and 15% by weight of bi-modal emulsifier compositions, which comprises:
(a) between 10% and 50% by weight of an emulsifier which conforms to the following structure:
xe2x80x83CH3(CH2)nxe2x88x92Oxe2x80x94(CH2CH2O)a(CH2CH(CH3)O)bxe2x80x94(CH2CH2O)cxe2x80x94H
xe2x80x83wherein;
n is an integer ranging from 5 to 19;
a, b, and c are independently each integers ranging from 0 to 20, with the proviso that a+b+c be greater than 5;
and
(b) between 90% and 50% of an emulsifier which conforms to the following structure: 
xe2x80x83wherein;
y is an integer ranging from 5 to 19, and is equal to n;
x is an integer ranging from 3 to 17 with the proviso that x=y+2
a, b, and c are independently each integers ranging from 0 to 20, with the proviso that a+b+c be greater than 5.
The various proviso listed above are a direct result of the fact that the alcohol undergoing the Aldol condensation is the exact same alcohol that makes up the non-guerbet portion of the composition. Clearly, the non-guerbet alcohol has a much lower molecular weight than the guerbet alcohol (half the molecular weight+18). When this bi-modal mixture is alkoxylated as a mixture, the result is an emulsifier pair with outstanding emulsification properties due in part to the bi-modal composition.
In a preferred embodiment n is 5, x is 3 and y is 5.
In a preferred embodiment n is 9, x is 7 and y is 9.
In a preferred embodiment n is 7, x is 5 and y is 7.
In a preferred embodiment n is 11, x is 9 and y is 11.
In a preferred embodiment n is 19, x is 17 and y is 19.
In a preferred embodiment a+c ranges from 10-40.
In a preferred embodiment b ranges from 1 to 20.
In a preferred embodiment a+c ranges from 10-40 and b ranges from 1 to 20.